The present invention relates to an apparatus installed downhole in a well bore for improving well control while servicing or replacing submersible pumps or other well flow control equipment. The use of submersible pumps and other equipment designed to improve well flow is commonly used to increasing the rate of production of wells that otherwise produce very slowly. However, pumps and other similar equipment suffer from a limited lifespan in relation to other well components, with pumps generally having a life about one-quarter that of other well components.
Such limited life components require frequent repair and/or replacement, and therefore such components must be withdrawn from the well at the end of their useful service life. Such removal requires that a well be opened; without means to close off the well or kill the well, the removal resulting in loss of well fluid into the surrounding environment, which is an undesirable occurrence. To prevent such spillage, various efforts have been made including the installation of valves or ball chokes beneath the pump. These efforts have been plagued by a variety of problems, including suffering from damage upon being pulled and run back into the hole, from low confidence in positioning, or an inability to function due to buildup in the well. A need therefore exists for a more reliable system of well control which is easily operated, resistant to damage, and not subject to time-consuming periods of waiting due to low confidence in downhole position.